Jig for installation of hinges



May 6, 1969 J. R. STEFFENS JIG FOR INSTALLATION OF HINGES Sheet Filed Dec. 22, 1966 S w 7 6 N y w 5 I E, 3 1H. 3 T J k f; z W; m w m M 4 1! UPI I I N l I. H 0 4/ 3 B 2 6 O I w .II .J 2% fl a I]. w o a Wm Z 9 U. m 's W0 -1 L, n 6 Z 5 5 H fa mm m w F 5 m 5 y 6, 1969 J. R. STEFFENS 3,442,308

JIG FOR INSTALLATION OF HINGES Filed Dec. 22, 1966 Sheet 5 of 2 49 QTI /4 4; 74

FIGA 4a FIG.6

FIGJO INVENTOR.

a 2 JOHN E. J'T FFE/Vs ..r WMQ 4 United States Patent 3,442,308 JIG FOR INSTALLATION OF HINGES John R. Steifens, 17341 Delia Ave., Orange, Calif. 92667 Filed Dec. 22, 1966, Ser. No. 603,844 Int. Cl. B270 /10; B27m 3/00; B27f 5/02 US. Cl. 144-27 14 Claims This invention relates to a jig for use in the installation of hinges, and more particularly to apparatus which is used in producing a multi-level mortise for the installation of a hinge.

A principal area of use of embodiments of the present invention is in' the installation of the concealed type hinge disclosed in Patent No. 1,984,092. Such hinges ordinarily include a butt plate and a centrally disposed integral housing, or compartment, which encloses the levers of the hinge. Their installation requires the forming of mortises having two depths and lengths in the door and also in the door jamb.

While such hinges have the advantage that they are concealed when the door is closed, there is considerable difficulty in installing them, which difficulty arises chiefly because of the necessity of providing mortises of two depths and lengths in the door and the door jamb. Despite past efforts to provide jigs or fixtures for the carpenter to facilitate doing the work, such jigs and apparatus fail to meet the requirements of portability, low cost manufacture, and rapidity of use required for good acceptance.

With the foregoing in mind, it is a major object of this invention to provide a new improved jig for use in installation of hinges.

Another object of this invention is to provide a low cost, easily manufactured jig for installation of hinges.

A further object of this invention is to provide a compact, portable jig for installation of Soss hinges.

It is still another object of this invention to provide a compact jig for use in providing mortises of two different depths and two different lengths in a door jamb, or door, for later installation of a hinge.

A further object of this invention is to provide an improved jig having a track section on which a router may be movably disposed and including means for easily adjusting said track section vertically to adjust the depth of the out of the router bit.

A still further object of this invention is to provide a jig for routing mortises for installation of hinges, which jig includes means for accurately positioning the mortise relative to the edge of the work.

Another object of this invention is to provide a jig for routing a mortise, which jig provides means for guiding the router as the router bit is moved into the work.

It is still another object of this invention to provide a jig having improved means thereon for limiting the longitudinal movement of a router along the jig to different predetermined lengths according to the vertical position of the router relative to the jig.

A further object of this invention to provide a jig for producing a multi-level mortise by a router disposed on a track section on the jig, which jig includes improved means for rapidly adjusting the elevation of the track section relative to the jig.

Other and further objects of this invention will become apparent in the detail description below in connection 'with the attached drawings wherein:

FIG. 1 is a perspective view of a preferred embodiment of the present invention as positioned on the edge of an illustrative door;

FIG. 2 is a front elevation view of the jig with the 3,442,308 Patented May 6, 1969 router in position to make the deepest portion of the mortise; I

FIG. 3 is a front elevation view of the jig with the router in position to make a more shallow out;

FIG. 4 is a fragmentary cross-sectional view of the assembly taken along line 4- 1 in FIG. 2;

FIG. 5 is a fragmentary cross-sectional view of the assembly taken along line 55 in FIG. 3;

FIG. 5a is a cross-sectional fragmentary view of part of the assembly taken along the same line as FIG. 5, but with the router carriage in the highest position relative to the jig assembly;

FIG. 6 is an enlarged fragmentary cross-sectional view disclosing some of the details of the means used in controlling the level of the elevation control track section;

FIG. 7 is an enlarged fragmentary cross-sectional view of a central portion of the jig, taken along line 77 in FIG. 4;

FIG. 8 is a preferred router mounting plate used in the assembly;

FIG. 9 is a fragmentary cross-sectional view of the door disclosing from the side the shallow portion of the mortise in the door;

FIG. 10 is an enlarged fragmentary cross-sectional view of the door disclosing from the side a two-level mortise produced with the .use of the present invention;

FIG. 11 is a plan view of a two-level mortise produced with the use of the present invention; and,

FIG. 12 is a perspective view of a marking gauge preferably used in conjunction with the present invention.

Referring now to the drawings there is shown a jig, indicated generally by the arrow 10, which jig is a first preferred embodiment of the present invention. The jig 10 is positioned on a door edge 11 and indexed by means which will be described below. The jig includes an elongated frame, indicated generally by the arrow 13, which has a longitudinal axis extending parallel to the plane of the door edge 11. Further details of the construction of the frame 13 will be described below.

Disposed for lineal movement along a track, to be described, is a carriage 14 on which is fixed a router 15 having a router bit 16 depending therefrom. As will be described in greater detail below the jig 10 operates such that the router bit may be moved to form a two-level mortise in the door edge 11. The shape of the two-level mortise can be seen best in FIGS. 10 and 11 where it can be seen that the mortise includes a central deep cavity 17 with a pair of shallow end cavities 18. With the router 15 in a lower position the router is moved along the longitudinally axis for a predetermined short distance to form the central deep cavity 17. With the router 15 positioned at a more elevated position, it may be moved longitudinally a longer distance than permitted when the router is in the lower position. Thereby, the shallow end cavities 18 result.

The preferred construction which results in the easy shifting of the elevation of the router 15 and the manner in which the carriage 14 cooperates therewith will now be described in further detail. The frame 13 includes an elongated main frame member 20 having a longitudinal groove 21 extending the length thereof to provide a rail, or track, portion 22 at the left end of the frame and a similar rail, or track, portion 23 at the right end of the 7 frame. Disposed between the rail portions 22 and 23 is an elevation control track section 24 which has at its top a rail 25 which may be moved between raised positions and a lower position in a manner to be described. For purposes of being guided, the carriage 14 includes a channel member 26 having a web with a pair of spaced depending legs, or flanges, which cooperate with and receive guiding support from the rail 25 and (when the track section 24 is in the lowest position) the rail portions 22 and 23.

The manner in which the elevation control track section 24 operates will now be described in further detail. As can be seen, the main frame member 20 is provided with a centrally disposed recessed notch 27 on the front thereof with a pair of upstanding posts 28 provided near the two ends of the notch. The track section 24 is slidably received in the notch 27 and is provided with suitably disposed vertical guide bores 29 which receive therein the posts 28 which provide partial support for the track section. With the above described arrangement, there is no obstruction to free movement of the carriage 14 along the top of the rail 25.

It is preferred that means be provided to limit the overall range of vertical motion of the track section 24. Accordingly, there is provided a centrally disposed vertical slot 31 in the track section 24 which receives a laterally projecting pin 32 which is press fit into the main frame member 20. With the track section 24 in the lowest position (shown in FIGS. 2, 4, and 7), the track section is at such a low position that the pin 32 is at the upper end of the slot 31. However, when the track section 24 is near its upper position, most of slot 31 will be above the pin 32.

As best can be seen in FIGS. 4, 5, and a, the track section 24 has a depending flange 34 extending along the front lower end of the track section-which flange has a stop edge 35 at its lower side for the purposes to be described.

Also centrally disposed in the main frame member 20 at a position just below the notch 27 is a recess 38 which receives therein a stop block 39 for purposes to be described. As mentioned previously, the track section 24 is disposed for vertical movement for purposes of controlling the level of the router relative to the frame 13. On the other hand, the stop block 39 is disposed for horizontal lateral movement at a right angle to the axis of the frame for purposes of selectively controlling the height of the track section 24. To the end of permitting such lateral movement, the stop block 39 is provided with a pair of guide bores 40 near the two respective ends, which guide bores receive in sliding relation guide pins 41 which are press fit into suitable holes in the main frame member 20. For purposes described below, a pair of springs 42 are located as shown to bias the stop block 39 forwardly relative to the frame member 20. For purposes of limiting the amount of motion of the stop block 39, there is provided a bolt 44 extending through the frame member into the stop block 39 where the bolt is threaded. It will be noted that the head of the bolt 44 is received into a counter bore 45 which is deep enough that the head of the bolt 44 will not project beyond rear face 46 when the stop block 39 is moved to its most rearwardly position. Therefore, the head of the bolt 44 will not engage the face of the door during operation.

As illustrated best in FIGS. 1, 4, 5, and 5a, the stop block 39 further includes an upper engagement face 47 with a lower engagement face 48 spaced slightly below the upper engagement face. The engagement faces 47 and 48 operate in the following manner. When the stop block 39 is pushed to its depressed or rearward position, the depending flange 34 extends in front of the stop block as in FIG. 4. Then, when the operator grasps the track section 24 by placing his fingers in finger grip recesses 50 and raises the section upward, the track section will move to the position shown in FIG. 5 at which point the stop block 39 will spring forward slightly to the position shown in FIG. 5. At this point, if there is force applied to the track section 24, any downward movement of the section will be prevented by engagement of the lower engagement face 48 with the downwardly facing stop edge 35. Then, when the operator pulls the track section 24 further upward to the position shown in FIG. 5a, the stop block 39 moves to the position shown in FIG. 511 where the upper engagement face 47 engages the stop edge 35.

It should be noted that the upper and lower engagement faces 47 and 48 extend a considerable portion of the length of the track section 24. Therefore, the stop block 39 support the track section 24 against motions trying to tilt the track section relative to the longitudinal axis of the frame 13, as well as, supporting the track section against being depressed by the weight of the carriage 14 and the supported equipment.

Left and right front plates 52 and 53 respectively are screwed to the front side of the main frame member 20 as disclosed. It will be noted that the front plates 52 and 53 extend toward each other sufliciently to overlap the track section 24, and therefore, they provide the function of helping to guide the track section by resisting forward movement of the track section. The front plates 52 and 53 also have the function of carrying part of the stop means which are used to limit the longitudinal motion of the router as desired. To this end, at the left end of the plate 52 there is provided an upstanding boss having a stop screw 54 threaded therethrough with a lock nut 57 provided to lock the screw in the desired position. A stop screw 56 at the right end of the plate 53 operates in a similar manner with a lock nut 57.

As best seen in FIG. 2, with the carriage 14 in the lower position left end 58 of the channel member 26 engages the stop screw 54 when the carriage is at the left end of its motion, and then when the carriage 14 is moved to the right, right end 59 of channel member 26 engages the stop screw 56. The stop screws 54 and 56 have the advantage that they may be easily adjusted by the operator to enable the subject jig to accommodate a wide range of hinges.

The stop screws 54 and 56 cooperate with the carriage 14 in order to provide a first means which will limit the longitudinal motion of the carriage 14 to a first predetermined distance when the carriage is in the lower position. When the carriage 14 is in either of the upper positions, a second stop means is provided to limit the range of the longitudinal motion of the carriage 14 to a second predetermined distance which is longer than the first predetermined distance. To this end, a headless screw 60 is threaded into the left side of the front plate 53 and then held at the desired position by means of a lock nut 61. Similarly headless stop screw 62 is threaded into the right end of the front plate 52 and then held by lock nut 63. For purposes of engaging said lock screws 60 and 62, there is provided on the carriage 14 a depending stop post 65 which is centrally disposed as shown.

With the track section 24 in either of the upper positions, the ends 58 and 59 of the channel member 26 are above the stop screws 54 and 56. However, the depending stop post 65 will engage the stop screws 60 and 62 to thus limit the longitudinal movement of the carriage 14 as desired.

With the portion of the apparatus already described, it can be seen that the track section 24 may be rapidly moved to its lower position by merely pressing the stop block 39 rearwardly and pushing the track section downward. Then when the operator desires to raise the track section, he merely pulls it up until it is at the level desired where it is supported by the desired engagement face 47 or 48.

In order to index the main frame member 20 relative to the door edge, left and right location plates 68 and 69 respectively are provided extending laterally from the longitudinal axis of the frame 13 in a direction opposite the side on which are located the front plates 52 and 53 and the stop means. It will be noted that the left location plate 68 is secured to the frame member 20 by means of a pair of screws 70 which extend through longitudinal slots 71. Thereby, the longitudinal position of the location plate 68 relative to the frame member 20 can be adjusted. Similar screws 72 (see FIGS. 4, 5, and 5a) to operate with longitudinal slot to adjustably affix the right location plate 69 to the main frame member 20.

Shifting now to further detail as to the manner in which the router 15 is mounted, it can be seen best in FIG. 8, that a circular mounting plate 76 is secured to the upper side of the channel member 26 with centrally disposed hole 77 provided to receive therethrough the router bit, or cutter, 16. It will be noted that there are a large number of holes 79 provided at different positions on the mounting flange 76 to permit a wide variety of routers to be bolted to the mounting flange by screws going through the holes 79.

It will be noted that the hole 77 is offset from the axis of the channel member 26. This is because, the channel member 26 is to one side of the door edge 11, or the door jamb, in which a mortise is desired to be made. Positioning the router bit 16 relative to the width of the door edge 11, or a door jamb, is quite important. Therefore, in order to increase accuracy, the mounting plate 76 is not rigidly fixed to the channel member 26. Rather, the mounting plate 76 is preferably, swingably secured to the channel member 26 by means of a riveter pin 81 which is swaged at both ends to provide a swinging joint. Then, in order to permit very accurate lateral adjustment of the central hole 77 (and therefore the bit 16), a curved slot 82 is disposed in the plate 76 and receives therethrough a screw 83 which is threaded into the upper side of the channel member 26. With this arrangement, after the router 15 has been bolted to the mounting flange 76, the mounting flange may be quickly and easily adjusted in order to increase the speed of the work.

Having described the details of the construction of the preferred embodiment of the invention, attention is now directed to the manner in which the preferred embodiment of the invention is used. The description will be in connection with the door edge 11 since that is shown in the drawings, and the operation of the unit may be accurately described in such frame of reference. However, it should be understood that in actual practice, the jig would be adjusted and tested initially on a practice piece of wood. Further, the carpenter will normally make the mortise in the door jamb first, and then in the door edge.

Firstly, the mounting plate 76 is adjusted so that the router bit 16 will be at the appropriate distance from the edge of the door jamb. The router 15 is mounted onto the plate 76 by means of screws through the holes 79. Preferably, the router 15 incorporates a /2 inch straight faced router bit 16 which is A; of an inch long in the router chuck. Preferably, the router bit is set depending about 1% inches below the mounting plate 76 in order to provide reasonable room. The location plates 68 and 69 are moved to the extreme outside ends of the main body 20. The stop screws 54, 56, 60, and 62 are adjusted so that the motion of the carriage 14 is limited to predetermined distances by engagement with said stop screws, and further said ranges of motion are centered relative to the frame member 20. The distances desired depends upon the particular hinges to be installed. At this time, the first cut in the door edge 11 is ready to be made.

The manner in making the first cut is an important aspect of the present invention. Considerable difficulty is encountered in previous devices in trying to start the cut. This is because, in prior devices, there was not sufiicient provision made for guiding support to the router during the time the router is in the intermediate phase of moving toward the position where a full cut is being made. In the present preferred embodiment, the extra guiding at the intermediate stage is accomplished in the following manner. The track section 24 is moved to its upper position desired. If the hinge being installed has the thicker mounting tabs on the butt plates, the stop edge 35 is put in engagement face 48 (FIG. 5). However, when installing the hinges with the thinner mounting flanges, i.e., when it is desired that the end cavities 18 are more shallow, the track section 24 is moved to the position of FIG. 5a and the upper engagement face 47 is positioned against the stop edge 34.

At this point, the carriage 14, with the router 15 thereon is in one of the operators hands, and he is holding the jig in position with his other hand. Then, end 59 of the channel member 26 is placed in the position in FIG. 1 engaging the stop screw 56 with the carriage in the tilted position shown. At this time, the router bit 16 does not engage the door edge 11. Then, the carriage 14 is tilted downward until the legs of the channel member 26 slide around the right end of the rail 25. At this time, the carriage 14 (and therefore the router 15) is receiving support against longitudinal motion by engagement with the stop screw 56, and receiving support against rotational motion around the axis of the channel member 26 by engagement of the legs of the channel member 26 with the front and rear of the rail 25 and the front and rear of the rail or track portion 23 and the top of the rail portion 23.

Just before the web of the channel member 26 engages the top of the rail 25, the router 16 will begin cutting the door edge 11. Then, after the right end of the rail 25 engages the web of the channel member 26, the carriage 14 is continued to be tilted toward horizontalcausing the bit 16 to cut further into the work. However, during this phase, the carriage 14 has good support by engagement of the channel member 26 legs and web with the rail 25 of the track section 24. When the carriage 14 is in the horizontal position, the carriage is moved back and forth between the stop screws 60 and 62 to thereby provide a shallow mortise 87 (see FIG. 9) in the door edge 11. When the mortise 87 is provided, the router 15 is removed, the stop block 39 is pushed inwardly and the track section 24 is lowered to the position shown in FIG. 2. Then, the operator tilts the router 15 as shown in FIG. 1 and engages right end 59 on the stop screw 56. At that time he swings the router bit 16 down into the work. It should be noted, that the engagement of the legs of the channel member 26 with the rail portion 23 provides good guiding support for the carriage 14, and therefore the router 15. When the carriage 14 reaches the horizontal position shown in FIG. 2, it is moved back and forth to provide the deep center cut 17 shown in FIGS. 10 and 11.

In the initial set up for a particular size hinge, the mortise would then be checked to make sure that the depths and lengths are correct. This is not required after the initial set-up. Then, in the initial set-up the location plates 68 and 69 are moved toward each other until the near edges of the plates are at the ends of the shallow end cavities or mortises 18. In subsequent operations, the location plates 68 and 69 will then quickly and accurately indicate to the operator the position of the shallow mortise 87, i.e., the overall length of the two-level mortise.

As mentioned previously the mortise is normally made in the door jamb first. This is done by the previously described steps. Then, it will be desired to make a similar two-level mortise in the door edge 11. To this end, there is provided a marking gauge which has a length equal to the butt plate portion of a hinge, i.e., the length of the hinge at the area of the mounting flanges. The gauge 90 also has a thickness substantially equal to the depth of the end cavities of the mortise in the jamb, and is provided with raised curved edges 91 at either end of the gauge 90. Therefore, the gauge 90 may be inserted in the upper lever of the two-level mortise. Then, the door is located at the desired position and tapped against the door jamb. The raised curved edges 91 will provide a marking indicate to the operator the position of the shallow mortise on the door edge.

As can be seen, with the present invention, it is not necessary to change the depth of the router bit in order to make a two-level mortise. Further, the guiding of the cutter bit into the work is positive. Additionally, the jig affords a simple operation with great reductions of time resulting from ease with which the depth of cut may be changed and the compactness of the unit.

While only a few embodiments of the present invention have been shown in and described it will be apparent to those skilled in the art that such is by way of illustration only and numerous changes may be made thereto without departing from the spirit of the present invention. Accordingly, it is intended that the invention be limited solely by the appended claims.

I claim:

1. A jig for use in the installation of hinges comprising:

an elongated frame having a longitudinal axis;

a lineal track on said frame extending along said axis;

an elevation control track section on said frame, said track section being vertically movable between a first lower position and a second upper position;

a carriage removably disposed on said track section for movement therealong in a lineal path, means on said carriage for mounting on said carriage a router having a d pending bit;

first stop mea s on said carriage and said frame for limiting said carriage movement along said track section to a first predetermined distance when said track section is in said first lower position;

and second stop means on said carriage and said frame for limiting said carriage movement along said track section to a second predetermined distance when said track section is in said second upper position, said first predetermined distance being substantially less than said econd predetermined distance.

2. The combination set forth in claim 1 wherein:

said track has a portion extending along said axis beyond said track section a substantial distance; and said carriage has a length sufficient that the carriage may be tilted to an angle to said axis and engage and receive guiding support from said track portion and-said track section in said angular position. 3. The combination set forth in claim 2 wherein: said first stop means includes a stop mounted on said frame in the path of an abutment on said carriage, and said stop is disposed on said frame in position to be engaged by said abutment when said carriage is in said tilted position. 4. The combination set forth in claim 1 wherein: a stop edge is provided on said track section at a point spaced below the upper edge of said track section;

and gauge block means are mounted on said frame for lateral movement between a first position out of the path of said stop edge when the track section is moved and a second position in the path of said stop edge when the track section is moved, whereby said gauge block means limits the vertical movement of said track section when said last mentioned means is in said second position but not when in said first position.

5. The combination set forth in claim 4 wherein:

said gauge block means has an upper engagement face and a lower engagement face spaced slightly below said upper engagement face;

and said gauge block means is movable laterally between a second position where said lower engagement face is in the path of said stop edge and a third position where said upper engagement face is in the path of said stop edge, whereby when said gauge block means is in said second position and said carriage stop edge is engaging it the carriage is in a lower position relative to the frame than when the block means is in said third position and engaged by the carriage stop edge.

6. The combination set forth in claim 5 wherein:

said gauge block means is biased in a direction from said second position toward said third position, whereby when said carriage is manually raised sulficiently the gauge block means will automatically move to said third position where said upper engagement. face will support said carriage by engagement with said stop edge.

7. The combination set forth in claim 4 wherein:

said stop edge extends a substantialy portion of the length of said track section and an engagement face engages said stop edge for nearly the entire length of said stop edge to support the track section near both ends of the track section, whereby the rigidity of the track section is increased.

8. The combination set forth in claim 1 wherein:

said carriage includes a downwardly facing channel member having a web and two spaced depending legs;

said track section has a rail as its upper edge;

and said channel member web and legs are engaged by said rail, whereby the engagement of said rail and said channel member guide said carriage as it is moved along said track section.

9. The combination set forth in claim 1 including:

a mounting plate on said carriage, said mounting plate having a plurality of holes for mounting thereon a router with a bit of the router extending downwardly, said mounting plate having a hole therethrough for receiving therethrough the bit of a router mounted on the plate, said hole being disposed laterally from said track section in a first direction.

10. The combination set forth in claim 9 including:

locating plates on said frame at either end of the frame, said locating plates extending in said first direction and having flat lower faces adapted to engage the edge of a door on which the jig is to be used in the installation of a hinge.

11. A jig for use in installation of hinges comprising:

an elongated frame having a longitudinal axis;

an upwardly facing lineal track on said frame extending along said axis;

an upwardly facing elevation control track section on said frame, said track section being movable relative to said frame between a first lower position and a second upper position;

a carriage disposed on top of said track and track section, said track section cooperating with said carriage to support the carriage against downward movement and lateral movement, said carriage being adapted to have mounted thereon a router having a bit extending downwardly from the router;

guide means on said frame for at least partially guiding said track section between said first and second positions in a lineal vertical movement;

gauge means mounted on said frame for selectively con-. trolling the height of said track section relative to said frame, said gauge means including a stop block mounted on said frame for movement between a second position where it at least partially supports said track section against tilting movement relative to said axis and limits the downward movement of said track section and a first position where it does not support the track section at the same level as when in the second position;

and stop means on said carriage and frame for limiting movement of said carriage along said track section to a first predetermined distance when said section is in said upper position and for limiting movement of said carriage along said track section to a second predetermined distance when said section is in said lower position, said first predetermined distance being substantially longer than said second predetermined distance.

12. The combination set forth in claim 11 including:

means connected to said frame biasing said stop block from one of said two positions toward the other of said two positions;

and a portion on said track section which portion holds 9 said block in said one position when said track section is in one of said first and second positions and does not hold said block in said one position when said track section is in the other of said first and second positions. 13. The combination set forth in claim 12 wherein: part of stop means is located on said guide means. 14. The combination set forth in claim 11 including: location plates on said frame disposed at either end of said frame, said location plates extending laterally from said axis and being adapted to engage the edge of a door in which the jig is to be used to install a hinge.

1 0 References Cited UNITED STATES PATENTS 1,718,324 6/1929 Wappat 144-70 3,082,800 3/1963 Soss 144-27 5 3,221,784 12/1965 Skollerud 144-27 X FOREIGN PATENTS 515,709 1/1931 Germany.

10 DONALD R. SCHRAN, Primary Examiner.

U.S. Cl. X.R. 14470, 144 

1. A JIG FOR USE IN THE INSTALLATION OF HINGES COMPRISING: AN ELONGATED FRAME HAVING A LONGITUDINAL AXIS; A LINEAL TRACK ON SAID FRAME EXTENDING ALONG SAID AXIS; AN ELEVATION CONTROL TRACK SECTION OF SAID FRAME, SAID TRACK SECTION BEING VERTICALLY MOVABLE BETWEEN A FIRST LOWER POSITION AND A SECOND UPPER POSITION; A CARRIAGE REMOVABLY DISPOSED ON SAID TRACK SECTION FOR MOVEMENT THEREALONG IN A LINEAL PATH, MEANS ON SAID CARRIAGE FOR MOUNTING ON SAID CARRIAGE A ROUTER HAVING A DEPENDING BIT; FIRST STOP MEANS ON SAID CARRIAGE AND SAID FRAME FOR LIMITING SAID CARRIAGE MOVEMENT ALONG SAID TRACK SECTION TO A FIRST PREDETERMINED DISTANCE WHEN SAID TRACK SECTION IS IN SAID FIRST LOWER POSITION; AND SECOND STOP MEANS ON SAID CARRIAGE AND SAID FRAME FOR LIMITING SAID CARRIAGE MOVEMENT ALONG SAID TRACK SECTION TO A SECOND PREDETERMINED DISTANCE WHEN SAID TRACK SECTION IS IN SAID SECOND UPPER POSITION, SAID FRIST PREDETERMINED DISTANCE BEING SUBSTANTIALLY LESS THAN SAID ECOND PREDETERMINED DISTANCE. 